TY  - JOUR
A1  - Lebiga, O.
A1  - Santos-Lima, Reinaldo
A1  - Yan, Huirong
T1  - Kinetic-MHD simulations of gyroresonance instability driven by CR pressure anisotropy
JF  - Monthly notices of the Royal Astronomical Society
N2  - The transport of cosmic rays (CRs) is crucial for the understanding of almost all high-energy phenomena. Both pre-existing large-scale magnetohydrodynamic (MHD) turbulence and locally generated turbulence through plasma instabilities are important for the CR propagation in astrophysical media. The potential role of the resonant instability triggered by CR pressure anisotropy to regulate the parallel spatial diffusion of low-energy CRs (less than or similar to 100 GeV) in the interstellar and intracluster medium of galaxies has been shown in previous theoretical works. This work aims to study the gyroresonance instability via direct numerical simulations, in order to access quantitatively the wave-particle scattering rates. For this, we employ a 1D PIC-MHD code to follow the growth and saturation of the gyroresonance instability. We extract from the simulations the pitch-angle diffusion coefficient D-mu mu produced by the instability during the linear and saturation phases, and a very good agreement (within a factor of 3) is found with the values predicted by the quasi-linear theory (QLT). Our results support the applicability of the QLT for modelling the scattering of low-energy CRs by the gyroresonance instability in the complex interplay between this instability and the large-scale MHD turbulence.
KW  - MHD
KW  - plasmas
KW  - turbulence
KW  - cosmic rays
Y1  - 2018
U6  - https://doi.org/10.1093/mnras/sty309
SN  - 0035-8711
SN  - 1365-2966
VL  - 476
IS  - 2
SP  - 2779
EP  - 2791
PB  - Oxford Univ. Press
CY  - Oxford
ER  -